Recent strategies targeting efficient hydrogen production from chemical hydrogen storage materials over carbon-supported catalysts

Abstract

There is an evident urgent need to find a renewable and clean energy vector to ensure the worldwide energy supply while minimizing environmental impacts, and hydrogen stands out as a promising alternative energy carrier. The social concern around its safe storage is constantly fostering the search for alternative options to conventional storage methods and, in this context, chemical hydrogen storage materials have produced abundant investigations with particular attention to the design of heterogeneous catalysts that can boost the generation of molecular hydrogen. Among the chemical hydrogen storage materials, formic acid and ammonia–borane hold tremendous promise, and some of the recent strategies considered for the preparation of high-performance carbon-supported catalysts are summarized in this review. The outstanding features of carbon materials and their versatility combined with the tunability of the metal active phase properties (e.g., morphology, composition, and electronic features) provide numerous options for the design of promising catalysts. Precise control over the size and composition of metal nanoparticles is critical to the safe production of hydrogen from chemical storage systems. Kohsuke Mori and Hiromi Yamashita from Osaka University in Japan and colleagues review recent progress in producing hydrogen gas for fuel cell technology from the energy-rich molecules formic acid and ammonia borane. By immobilizing nanosized metal catalysts onto carbon-based supports with shapes including ultrasmall spheres, nanotubes, and graphene oxide sheets, researchers can tune hydrogen generation rates to record-high levels while still ensuring easy recovery and reuse. Catalytic reactions with formic acid can be improved by using noble metal-based palladium catalysts. While ruthenium nanocatalysts are favored for ammonia borane reactions, less expensive metal nickel and cobalt nanoparticles are gaining attention. This review recapitulates some of the most representative studies recently reported on carbon-supported catalysts for the hydrogen production from formic acid and ammonia borane by considering both active phase features and support properties. Several synthetic strategies are herein summarized to highlight the versatility of carbon materials in affording highly-performing catalysts for the hydrogen production from hydrogen carrier molecules.